Issue 118: Parse <!DOCTYPE>

Reported by Nikolaus Schaller, Aug 2, 2010

Should result in

#document  DOMHTMLDocument
  html     DOMDocumentType
  HTML     DOMHTMLHtmlElement
etc.

I.e. <!DOCTYPE> should generate a child of the the DOMdocument 
that represents the doctype. The name should be the type.

Comment 1 by Nikolaus Schaller, Nov 22, 2013

We also should load DTDs (or have a locally cached version of the 
most common ones) to handle XHTML and <!ENTITY> definitions

Comment 2 by Samantha Letcher, Dec 17, 2019

This is the type of some documents also many docs wrote like this 
which one understands for some special person or technician. Here 
are some examples in it 
https://writeessaysforme.com/research-proposal/ this will helpful 
for you to understand and to use.

Small WebKit